<aside class="panel panel-default panel-widget">
    <div class="panel-heading">热门话题</div>
    <ul class="list list-group topics-widget">
         {% for topic in topics %}
        <li class="list-group-item">
            <a href="{{ path('user_view', {'username': topic.user.username}) }}"><img src="{{ asset(topic.user.avatar)|imagine_filter('middle_square') }}"  class="avatar img-circle"/></a>
            <a href="{{ path('topic_view', {'id': topic.id}) }}">
                {{ topic.title }}
            </a>
        </li>
        {% endfor %}
    </ul>
</aside>